Sky and Telescope - March 2018 - 50

MARCH 2018 OBSERVING
Celestial Calendar

Action at Jupiter
JUPITER LINGERS in Libra this spring.

Asteroid Occultations
VERY EARLY on the morning of March

14th, the faint asteroid 51 Nemausa
will black out an 11.5-magnitude star in
the constellation Sextans. The star will
appear to dim to 10.2 (the magnitude
of Nemausa) for up to 15.7 seconds for
viewers along a path running from New
Jersey across western New York and
Lake Ontario to Nunavut. The occultation for observers in the United States
will happen within a minute or two of
4:43 UT (12:43 a.m. EDT) on the 14th.
On the morning of March 26th the
very faint asteroid 88 Thisbe will occult
a 12th-magnitude star in Sagittarius.
Though the event track stretches across
North America, the Sun will be well up
for the eastern United States by the time
the occultation occurs, so this one is
for viewers in the American West. The

Minima of Algol

occultation will begin within a minute
or so of 12:59 UT (5:59 a.m. PDT) and
will last at most 7.7 seconds.
About a week before both events,
more precise predictions and path maps
will be available from Steve Preston's
asteroid and minor-planet occultation
website (asteroidoccultation.com).
For advice on timing occultations and
reporting observations, see asteroidoccultation.com/observations.

GET INVOLVED
º If you'd like to learn how to time asteroid

occultations, start by downloading the
free ebook Chasing the Shadow: The IOTA
Occultation Observer's Manual from Derek
Breit's occultation page (poyntsource.
com/IOTAmanual).

Aldebaran Afternoon
THE MOON will be a waxing crescent,

Feb.

UT

Mar.

UT

2

4:30

2

20:43

5

1:19

5

17:32

7

22:09

8

14:22

10

18:58

11

11:11

13

15:47

14

8:00

16

12:37

17

4:50

19

9:26

20

1:39

22

6:15

22

22:28

25

3:05

25

19:17

27

23:54

28

16:07

31

12:56

These geocentric predictions are from the
heliocentric elements Min. = JD 2452500.179
+ 2.867335E, where E is any integer. For a
naked-eye comparison-star chart and more
information about Algol and its history, see
skyandtelescope.com/algol.

50

M A RCH 2 018 * SK Y & TELESCOPE

31% lit, when it occults Aldebaran on
the afternoon or evening of Thursday,
March 22nd. Observers in the northwestern United States and western Canada can try to spot the 1st-magnitude
star as it disappears behind the Moon's
dark limb and reappears at the bright
limb some 30-35 minutes later. Observers along the southern edge of the path
should be alert and look for a graze
along the southeastern lunar limb.
Complete timetables for the event
are available from the International
Occultation Timing Association (lunaroccultations.com/iota/bstar/bstar.
htm), but these will get you started:

Anchorage, disappearance 5:43 p.m.,
reappearance 6:43 p.m. AKDT; Vancouver, BC, d. 2:50 p.m., graze 3:02 p.m., r.
2:38 p.m. PDT; Seattle, d. 2:53 p.m., gr.
3:04 p.m., r. 3:20 p.m. PDT; Edmonton,
d. 4:05 p.m., gr. 4:20 p.m., r. 4:46 p.m.

The gas giant reaches its easternmost
stationary point at 10h UT March 9th,
then begins retrograde motion, on its
way to a May 9th opposition. Jupiter
brightens from magnitude -2.2 to -2.4
during the course of the month and
broadens in equatorial diameter from
39″ to more than 42″.
Any telescope shows Jupiter's four big
Galilean moons, and binoculars usually show at least two or three. Use the
diagram on the facing page to identify
them at any date and time.
All of the March interactions
between Jupiter and its satellites and
their shadows are tabulated on the facing page.
And here are the times, in Universal
Time, when the Great Red Spot should
cross Jupiter's central meridian. The
dates, also in UT, are in bold. (Eastern
Daylight Time is UT minus 4 hours.)
March 1, 9:34, 19:30; 2, 5:25, 15:21;
3, 1:17, 11:12, 21:08; 4, 7:04, 16:59; 5,
2:55, 12:51, 22:46; 6, 8:42, 18:37; 7,
4:33, 14:29; 8, 0:24, 10:20, 20:16; 9,
6:11, 16:07; 10, 2:02, 11:58, 21:54; 11,
7:49, 17:45; 12, 3:41, 13:36, 23:32; 13,
9:27, 19:23; 14, 5:19, 15:14; 15, 1:10,
11:06, 21:01; 16, 6:57, 16:52; 17, 2:48,
12:44, 22:39; 18, 8:35, 18:30; 19, 4:26,
14:22; 20, 0:17, 10:13, 20:08; 21, 6:04,
16:00; 22, 1:55, 11:51, 21:46; 23, 7:42,
17:38; 24, 3:33, 13:29, 23:24; 25, 9:20,
19:16; 26, 5:11, 15:07; 27, 1:03, 10:58,
20:54; 28, 6:49, 16:45; 29, 2:40, 12:36,
22:32; 30, 8:27, 18:23; 31, 4:18, 14:14.
April 1, 0:10, 10:05, 20:01; 2, 5:56,
15:52; 3, 1:48, 11:43, 21:39; 4, 7:34,
17:30; 5, 3:26, 13:21, 23:17; 6, 9:12,
19:08; 7, 5:03, 14:59; 8, 0:55, 10:50,
20:46; 9, 6:41, 16:37; 10, 2:33, 12:28,
22:24; 11, 8:19, 18:15; 12, 4:11, 14:06;
13, 0:02, 9:57, 19:53; 14, 5:48, 15:44;
15, 1:40, 11:35, 21:31; 16, 7:26, 17:22;
17, 3:17, 13:13, 23:09; 18, 9:04, 19:00;
19, 4:55, 14:51; 20, 0:47, 10:42, 20:38;
21, 6:33, 16:29; 22, 2:24, 12:20, 22:16;
23, 8:11, 18:07; 24, 4:02, 13:58, 23:54;
25, 9:49, 19:45; 26, 5:40, 15:36; 27,
1:31, 11:27, 21:23; 28, 7:18, 17:14; 29,
3:09, 13:05, 23:00; 30, 8:56, 18:52.
http://www.asteroidoccultation.com http://www.asteroidoccultation.com/observations http://www.asteroidoccultation.com/observations http://poyntsource.com/IOTAmanual http://poyntsource.com/IOTAmanual http://www.lunar-occultations.com/iota/bstar/bstar.htm http://www.lunar-occultations.com/iota/bstar/bstar.htm http://www.lunar-occultations.com/iota/bstar/bstar.htm http://www.skyandtelescope.com/algol
Sky and Telescope - March 2018

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